In order to protect occupants in an emergency or in a collision of a vehicle, airbag devices for a driver's seat and a passenger's seat are used. An airbag device inflates and deploys an airbag in front of an occupant, and the occupant is received and restrained by the airbag. Furthermore, conventionally, an airbag device having a double-walled airbag, which includes an outer bag and an inner bag, is known (see PTL 1).
In the conventional airbag device, the inner bag is inflated with gas supplied from an inflator. The gas flows into the outer bag through a circulation port in the inner bag, inflating the outer bag around the inner bag. An occupant is received by the inflated outer bag.
Such a double-walled airbag may allow the gas to flow from the inner bag toward the occupant, depending on the properties and deployment behavior required for the airbag. The inner bag is inflated inside the outer bag while allowing the gas to flow toward the occupant. At this time, if the occupant is in close vicinity of the airbag device, the occupant is received by the airbag that has not yet been fully inflated. In such a case, the occupant may collide with the inflating inner bag and receive impact. Furthermore, the impact applied to the occupant may increase due to the gas flowing toward the occupant from the inner bag. Therefore, such an airbag device has room for improvement, from the standpoint of suppressing damage to the occupant.